Sandwich panels consist of outer or face sheets separated by an inner core connected to their inside surfaces. They possess a high strength-to-weight ratio since they are light in weight and the core is configured to resist bending of the panel under stress. The inner core may be corrugated in one direction, corrugated in two directions, or have a waffle-type construction. Although they are relatively economical to produce, they have inherent weakness in certain directions of applied force and are weakened in bending stiffness to a greater or lesser degree because of the continuous linearity of the corrugation or waffle grids.
A typical honeycomb panel with an isotropic core provides good bending stiffness in all directions. While such panels exhibit good physical properties they are inherently more costly because of the core configuration itself.